Since i had a lot fun with this and i hope it turns into a great game, i think i should give some feedback.
Let's start with the game so far, it's simple and not a lot into it, but has the bones of a fun game. The combat is very simple and doesnt waste time. But you get too strong so easily, just buy the last bow and you can 1 or 2 shot every enemy until the boss.The armor also feels a bit strange, you get a full plate armor from a random old man, and it's supposed to be a decent armor at that. A normal hunter would have difficulty even moving in something like that. It would be better to be a simpler and less eye catching thing. Perhaps a simple breastplate and some arm and leg protections. It would fit a common soldier more. A fullplate armor would be something for a more high ranked knight or soldier.
The story is fine so far, a bit rushed, but nothing too out of place. The interactions with the succubus also feel fine, since they are not close right now.
The porn is also really good, but if i can give my two cents, you should probably not focus too much in the death draining, since you cant really progress or develop from then, since it always will end there. Sure you can make variations but there are limits there. A more femdom approach with the allied succubi is probably better in the long run, since you can always progress and make then "grow". But don't make a mistake to try and make the succubi only make relations with the MC, at least not until much latter when he grows into power and can take the drain without taking too much of a toll. If you are afraid of backlash, just dont make it too visible, like making people watch them feeding with others, just make that the player understand they are not exclusive to him.
A way to develop scenes you be escalating the feeding until he agrees to let them drain him. You could make a scene if you let them drain before the relationship develops, they kill you, but if you are close enough they let you barely alive. Other opportunities would be that you can let them drain you to make so they can do something story related, like helping them develop a spell or help in research, something that gives you a bonus in the long run. Perhaps if you let them drain you, you get a debuff for the fight for a few days.
Another thing is each succubus should have a motive to want to feed from you, like some want to make you let them kill you, or some want to corrupt you (so a succubus hater becomes addicted to succubi) or they just want to make you loosen up. Perhaps you can make a pact with them so they dont kill their prey, if you feed them beforehand.
Relationships and characters that develop are much better than just instant gratification of some death rape in the end. Not that we cant have fun with them.
And i think the MC should grow in the game, like the more he feeds the succubi the more resistent he should become, makes no sense that a weak succubus can easily drain you if you are much more powerful. There should be a limit a succubus can take before they are full. Dont mistake that with the MC being dominant, just harder to pass out or die from drain.
If you read so far, thanks. Hope if can be useful for you. Just know i'm not a game developer and maybe my opinion is full of shit, but i think as gamer maybe i have some useful insight.